The tracks of tracked vehicles such as tanks generally comprise rectilinear links which are articulated together and pass successively around the periphery of a substantially circular drive wheel or sprocket which is provided on the output side of a terminal drive which can be mounted on a wall of the vehicle, such as a tank hull, and which has its input side connected to the drive train of the vehicle. Since the chain engages the drive wheel as a polygon rolling on a cylindrical surface, the interaction between the drive wheel and the chain is nonuniform, i.e. intermittent loads are applied to the drive wheel, even though a continuous tension is developed on the chain, and the forces transmitted to the axis of the drive wheel vary between a maximum and a minimum as each link engages and swings around the drive wheel.
Thus the runoff speed of the chain alternates between a maximum value as the link lies tangentially to the wheel and is positively driven thereby and a minimum value intermediate these maximum values as new links successively reach the drive wheel and are swung therearound.
This repetitive variation in the runoff speed gives rise to periodic accelerations and decelerations of the vehicle mass and the track which results, not only in high wear of the joints between the track links, of the portions of the track chain engaged by the wheel and of the portions of the wheel engaging the track, but also, especially at high speeds of the vehicle, in a significant jolting of the personnel in the vehicle. Such periodic oscillations have also been found to detrimentally affect the highly sensitive optical devices usually present in tanks and similar track-laying military vehicles.
It has already been proposed to provide the chain-drive wheel with an elastomeric ring to cushion these periodic oscillations and damp the shocks generated by the nonuniform speeds of the portions of the chain or track as they pass around the drive wheel.
It has been found, however, that such elastomeric rings are subject to squeezing effects which excessively load the rubber in the regions thereof surrounding the crown about which they were disposed, thereby generating heat which results in deterioration of the rubber.